This invention relates to a multiple-valve internal combustion engine for a motorized vehicle wherein four intake valves and two exhaust valves are provided for each cylinder.
Engines having multiple-valves are well known in the art. Examples of such engines are disclosed in the following U.S. Patents:
______________________________________ 4,363,300 - Honda 4,471,730 - Honda 4,495,903 - Asano 4,549,510 - Miyakoshi 4,615,309 - Yoshikawa 4,617,881 - Aoi et al 4,624,222 - Yoshikawa 4,637,356 - Kuroda 4,637,357 - Ohmi 4,638,774 - Aoi 4,660,529 - Yoshikawa ______________________________________
From an efficiency standpoint, the engines disclosed in these patents have failed to provide a desirable engine. Multiple valve engines generally require a large surface area for placement as described in the latter patents. However, to accommodate valves as large as possible within the chamber, individual valve seats and specifically the exhaust valve seats are very closely disposed, resulting in high thermal loading. This reduces the efficiency of the engine and thus the advantages of the use of multiple valves is offset by this disadvantage. There is also a practical limit to the types of actuating elements that may be used for the valves and this further determines valve placement.
Accordingly, there remains a need in the industry for a multiple valve motorcycle engine that resists high thermal loading and provides maximum output through the use of more valves.